Hi Kirk
Thanks for your help in trying to sort this out.
I have just done the following:
1. Went into the Photo Mechanic preferences and clicked on the 'IPTC/XMP' tab, clicked the lightening bolt and selected 'Adobe products'. It changed the settings so that it only created sidecar files.
2. Injested the files from a CF card to my hard drive (taken with Canon 5D Mk III)
3. Closed Photo Mechanic
4. Opened Lightroom
5. Import, and added the files from the folder I imported them to.
6. Set the rating on a photo to 3 stars.
7. Pressed ctrl-e to edit the file - it opened in Photoshop.
8. If I looked at the 'File -> File Info...' it says that it isn't rated (in fact there is very little XMP info in the file at all). If I save the photo in Photoshop, it saves it and Lightroom displays the edited photo, but there is no rating on the edited photo - just like before.
So, unfortunately this hasn't made any difference.
So, I did the following:
1. Removed all those photos from Lightroom.
2. Navigated to the folder in Windows Explorer
3. Deleted all the sidecar files
4. Reimported the photos into Lightroom
5. Set the rating on a photo to 3 stars
6. Edit in Photoshop
7. And it works! The rating in file info shows as 3 stars, and when I save it in Photoshop it appears back in Lightroom as 3 stars.
It seems like Photo Mechanic is doing something weird with the XMP sidecar files on the 5D Mk III that Lightroom doesn't like. If you want me to send you one of the sidecar XMP files that it is creating I'd be happy to do that.
So, this is a work around for any work in the future, but it does seem something is screwy with the sidecar files, and it doesn't fix my current problem, as if I use the tool to delete the XMP data, and then update the metadata in Lightroom, it undoes any colour correcting that we have had done already on all the photos in the Develop module on Lightroom.
Let me know your thoughts.
Thanks
Paul